Fields, impedances, and structures
King‐Yuen Ng · AIP conference proceedings · 1989
Beam particles interact directly with other beam particles or indirectly through the electromagnetic fields reflected back from the walls of the vacuum chamber. The interaction between the fields and a bunch may lead to coherent motions of the particles inside the bunch resulting in instabilities. In the frequency domain, we say that the beam current sees longitudinal and transverse impedances due to space charge and the discontinuities of the vacuum chamber. In this chapter, we first discuss the electromagnetic fields left by a particle after traversing some structures of the vacuum chamber. Next, coupling impedances are defined in terms of the wakefields. They are then estimated for various discontinuities in the chamber. (AIP)